Valeri A M, Wilson S M, Feinman R D
Biochim Biophys Acta. 1980 Aug 7;614(2):526-33. doi: 10.1016/0005-2744(80)90241-7.
Experiments were performed to determine if the sulfhydryl protease, papain (EC 3.4.22.2), reacts with the plasma protease inhibitor antithrombin (antithrombin III, heparin cofactor) on a specific manner analogous to the reaction of thrombin (EC 3.4.21.5) and other serine proteases with this inhibitor. The esterolytic activity of papain is blocked by the addition of antithrombin, but not by antithrombin-thrombin complex or by protein substrates such as bovine serum albumin. Likewise, in the presence of papain, antithrombin was unable to displace the active site dye proflavine from thrombin, or to inhibit thrombin-catalysed hydrolysis of an anilide substrate. The reaction of antithrombin and papain was not accelerated by low concentrations of heparin. Approximately stoichiometric amounts of heparin completely inhibited the reaction of papain with antithrombin. The mutual inhibition indicates that plasma antithrombin does react with papain but the reaction differs from the interaction with coagulation factors, particularly in the heparin effect.
开展实验以确定巯基蛋白酶木瓜蛋白酶（EC 3.4.22.2）是否以类似于凝血酶（EC 3.4.21.5）和其他丝氨酸蛋白酶与该抑制剂反应的特定方式与血浆蛋白酶抑制剂抗凝血酶（抗凝血酶III，肝素辅因子）发生反应。添加抗凝血酶可阻断木瓜蛋白酶的酯解活性，但抗凝血酶 - 凝血酶复合物或蛋白质底物（如牛血清白蛋白）则不能。同样，在木瓜蛋白酶存在的情况下，抗凝血酶无法从凝血酶上置换活性位点染料原黄素，也无法抑制凝血酶催化的苯胺底物水解。低浓度肝素不会加速抗凝血酶与木瓜蛋白酶的反应。大约化学计量的肝素完全抑制木瓜蛋白酶与抗凝血酶的反应。这种相互抑制表明血浆抗凝血酶确实与木瓜蛋白酶发生反应，但该反应与凝血因子的相互作用不同，特别是在肝素效应方面。
